Invasive medical probes or catheters used for cardiac procedures typically use electrodes in order to acquire potentials of a region of the heart being investigated or being operated on. The electrodes may also be used to inject current into the heart, for example for ablation, pacing, or for determining a location of the probe. In order to minimize trauma to the patient involved, the probe typically has a diameter that is as small as possible,
The small size of the probes consequently means that the electrodes of the probes have a correspondingly extremely small size. Furthermore, in some cases it is desirable that one probe should have a number of electrodes that are spatially separated and electrically insulated from each other. Such multiple electrode probes can be used for simultaneous potential acquisition from, and/or simultaneous ablation of, spatially separated sites in the heart. However, the multiple electrodes of necessity have to be of an extremely small size.
Other types of procedures using electrodes, such as electroencephalographic procedures, also benefit from using small probes with extremely small electrodes, so as to minimize trauma to patients.
U.S. Patent Application 2013/0060245, to Grunewald et al., whose disclosure is incorporated herein by reference, describes an ablation catheter adapted for direct tissue contact. The catheter is stated to have micro-elements that provide more accurate sensing of tissue, including thermal and electrical properties for temperature and impedance measurements. The micro-elements extend through a hollow chamber of an irrigated ablation electrode, and distal ends of the micro-elements can protrude outside of the electrode or be flush with the electrode.
Japanese Patent Publication JP2000-235995, to Kyomasu Ryuichi, whose disclosure is incorporated herein by reference, describes a ball forming method for wire bonding. The disclosure states that a high voltage is applied between the tip of a wire extending from the bottom of a capillary and a discharge electrode, forming a ball at the tip of the wire.
Documents incorporated by reference in the present patent application are to be considered an integral part of the application except that, to the extent that any terms are defined in these incorporated documents in a manner that conflicts with definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered.